Implantable micro-biosensor and method for operating the same

ABSTRACT

An implantable micro-biosensor includes a substrate, a first working electrode, at least one second working electrode, and at least one counter electrode. The first working electrode includes a first sensing section driven by a first potential difference to measure a physiological signal. The second working electrode includes a second sensing section driven by a second potential difference to consume an interfering substance. The counter electrode cooperates with the first working electrode to measure the physiological signal, cooperates with the second working electrode to consume the interfering substance, and selectively cooperates with the first or second working electrode to regenerate silver halide.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority of U.S. Provisional Application No.62/882,162, filed on Aug. 2, 2019, and U.S. Provisional Application No.62/988,549, filed on Mar. 12, 2020, both of which are incorporated byreference herein in its entirety.

FIELD

The disclosure relates to a micro-biosensor, and more particularly to animplantable micro-biosensor for continuously monitoring a physiologicalparameter of an analyte in a body. The disclosure also relates to amethod for operating the implantable micro-biosensor.

BACKGROUND

The rapid increase in the population of diabetic patients emphasizes theneed to monitor and control the variation of glucose concentration in abody of a subject. As a result, many studies are moving towards thedevelopment of implantable continuous glucose monitoring systems, so asto address the inconvenience associated with repeated procedures ofblood collection and tests. The basic configuration of the continuousglucose monitoring system includes a biosensor and a transmitter. Thebiosensor measures a physiological signal in response to a glucoseconcentration in the body, and the measurement thereof is mostly basedon an electrochemical process. Specifically, glucose is subjected to acatalysis reaction with glucose oxidase (GOx) to produce gluconolactoneand a reduced glucose oxidase, followed by an electron transfer reactionbetween the reduced glucose oxidase and oxygen in a biological fluid ofthe body to produce hydrogen peroxide (H₂O₂) as a byproduct. The glucoseconcentration is then derived from an oxidation reaction of thebyproduct H₂O₂. The reaction mechanism of the electrochemical process isshown below.

Glucose+GOx(FAD)→GOx(FADH₂)+Gluconolactone

GOx(FADH₂)+O₂→GOx(FAD)+H₂O₂

In the above reaction mechanism, FAD (i.e., flavin adenine dinucleotide)is an active center of GOx.

However, if interfering substances, such as ascorbic acid (a majorcomponent of vitamin C), acetaminophen (a common analgesic ingredient),uric acid, protein, glucose analogs, or the like, are present in theblood or the tissue fluid and the oxidation potentials thereof areproximate to the oxidation potential of H₂O₂, the measurement of glucoseconcentration will be adversely affected. Therefore, it is difficult toensure that the physiological parameters of a subject are trulyreflected by the measurement values and to maintain a long-termstability of the measured signal when the continuous glucose monitoringsystem is in operation.

At present, the aforesaid shortcomings are solved, for example, byproviding a polymer membrane to filter out the interfering substances.However, it remains difficult to filter out the interfering substancescompletely. Alternatively, a plurality of working electrodes optionallycoated with an enzyme or different types of enzymes are respectivelyapplied with potentials to read a plurality of signals from the workingelectrodes. The signals are then processed to accurately obtain thephysiological parameter of the analyte. However, such conventionalprocesses, which involves the use of the working electrodes, are verycomplicated.

In addition, stable sensing potentials can be obtained by using asilver/silver chloride as a material of the reference electrode or thecounter/reference electrode. Silver chloride of the reference electrodeor the counter electrode should be maintained at a minimal amountwithout being completely consumed, so as to permit the biosensor to bestably maintained in a test environment for measuring the physiologicalsignal and for achieving a stable ratio relationship between thephysiological signal and the physiological parameter of the analyte tobe detected.

However, silver chloride would be dissolved, resulting in the loss ofchloride ions, which will cause a shift of the reference potential. Whenthe silver/silver chloride is used for the counter electrode so as to beactually involved in a redox reaction, silver chloride would be evenmore consumed by reduction of silver chloride to silver. Accordingly,the service life of the biosensor is often limited by the amount ofsilver chloride on the reference electrode or the counter electrode. Theproblem is addressed by many prior arts. For example, in thetwo-electrode system, the counter electrode has a consumption amount ofabout 1.73 mC/day (microcoulomb/day) under an average sensing current of20 nA (nanoampere). That is, if the biosensor is intended to be buriedunder the skin of the body for continuously monitoring glucose for 16days, a minimum consumption capacity of 27.68 mC is required. Therefore,existing technology attempts to increase the length of the counterelectrode to be greater than 10 mm. However, in order to avoid beingimplanted deeply into subcutaneous tissue, the biosensor needs to beimplanted at an oblique angle, which results in problems such as alarger wound, a higher infection risk, and the like. In addition, thepain caused by the implantation is more pronounced.

Along with the development of a miniaturized version of the continuousglucose monitoring system, development of a biosensor that can improvethe measurement accuracy, extend the service life, simplify themanufacturing process, and reduce the manufacturing cost, is an urgentgoal to be achieved.

SUMMARY

Therefore, a first object of the disclosure is to provide an implantablemicro-biosensor which has an accurate measurement and an extendedservice life, and which can monitor a physiological parameter of ananalyte continuously.

A second object of the disclosure is to provide a process forcontinuously monitoring a physiological parameter of an analyte in abody using the implantable micro-biosensor.

According to a first aspect of the disclosure, there is provided animplantable micro-biosensor for continuously monitoring a physiologicalparameter of an analyte in a body. The implantable micro-biosensorincludes a substrate, a first working electrode, at least one secondworking electrode, and at least one counter electrode.

The substrate has a first surface and a second surface opposite to thefirst surface.

The first working electrode includes a first sensing section disposed onthe first surface of the substrate. The first sensing section is drivenby a first potential difference, so as to form a measuring region tomeasure a physiological signal in response to the physiologicalparameter of the analyte.

The at least one second working electrode is disposed on the firstsurface of the substrate, and includes a second sensing sectionproximate to the first sensing section. The second sensing section isdriven by a second potential difference to form aninterference-eliminating region that is in touch with a surrounding ofthe first sensing section and at least partially overlaps with themeasuring region, so as to consume an interfering substance in the bodywhich approaches the first and second sensing sections.

The at least one counter electrode is disposed on the first or secondsurface of the substrate, and includes a silver/silver halide, so as tocooperate with the first working electrode to measure the physiologicalsignal, to cooperate with the second working electrode to consume theinterfering substance, and to selectively cooperate with the first orsecond working electrode so as to be driven to regenerate silver halide.

According to a second aspect of the disclosure, there is provided aprocess for continuously monitoring a physiological parameter of ananalyte in a body during a monitoring time period that includes at leastone first time section for measuring the analyte, at least one secondtime section for consuming an interfering substance in the body, and atleast one third time section for regenerating silver halide. The processincludes the steps of:

a) providing the implantable micro-biosensor described above;

b) applying the first potential difference between the first workingelectrode and the counter electrode during the first time section topermit the first working electrode to have a potential higher than thatof the counter electrode so as to obtain the physiological signal;

c) applying the second potential difference between the second workingelectrode and the counter electrode during the second time section topermit the second working electrode to have a potential higher than thatof the counter electrode so as to consume the interfering substance; and

d) subjecting the counter electrode to be driven by a third potentialdifference so as to regenerate the silver halide.

In the implantable micro-biosensor according to the disclosure, thefirst working electrode, the at least one second working electrode, andthe at least one counter electrode are included, and a relative positionof the first sensing section and the second sensing section is assigned,such that the implantable micro-biosensor according to the disclosurenot only can execute the measurement of the analyte and reduce theinfluence of the interfering substances, but also can regenerate silverhalide by applying a potential difference to the counter electrode.Measurement of the analyte, reduction of the influence of theinterfering substances, and regeneration of silver halide may beadjustably performed according to practical needs. Therefore, theimplantable micro-biosensor according to the disclosure has an accuratemeasurement and an extended service life, and can monitor aphysiological parameter of an analyte continuously.

BRIEF DESCRIPTION OF THE DRAWINGS

Other features and advantages of the disclosure will become apparent inthe following detailed description of the embodiments with reference tothe accompanying drawings, of which:

FIG. 1 is a schematic view illustrating Embodiment 1 of an implantablemicro-biosensor according to the disclosure;

FIG. 2 is a schematic sectional view taken along line II-II of FIG. 1;

FIG. 3 is a schematic sectional view taken along line III-III of FIG. 1;

FIG. 4 is a schematic sectional view taken along line IV-IV of FIG. 1;

FIG. 5 is a schematic section view illustrating an interaction between afirst sensing section and a second sensing section of Embodiment 1;

FIG. 6 is a schematic view illustrating a configuration of a variationof Embodiment 1;

FIG. 7 is a schematic sectional view taken along line VII-VII of FIG. 6;

FIG. 8 is a schematic view illustrating a variation of the configurationof the second surface of Embodiment 1;

FIG. 9 is a schematic sectional view taken along line IX-IX of FIG. 8;

FIG. 10 is a fragmentary schematic view illustrating a variation of theconfiguration of the first surface of Embodiment 1;

FIG. 11 is a schematic sectional view taken along line XI-XI of FIG. 10;

FIG. 12 is a schematic sectional view taken along along line XII-XII ofFIG. 10;

FIG. 13 is a fragmentary schematic view illustrating another variationof the configuration of the first surface of Embodiment 1;

FIG. 14 is a schematic sectional view taken along along line XIV-XIV ofFIG. 13;

FIG. 15 is a schematic sectional view taken along along line XV-XV ofFIG. 13;

FIG. 16 is a schematic view illustrating a configuration of Embodiment 2of the implantable micro-biosensor according to the disclosure;

FIG. 17 is a schematic sectional view taken along line XVII-XVII of FIG.16;

FIG. 18 is a schematic sectional view taken along line XVIII-XVIII ofFIG. 16;

FIG. 19 is a schematic sectional view taken along line XIX-XIX of FIG.16;

FIG. 20 is a schematic section view illustrating an interaction betweenone first sensing section and two second sensing sections of Embodiment2;

FIG. 21 shows fragmentary schematic views illustrating variations of aconfiguration of a first sensing section of a first working electrodeand a second sensing section of a second working electrode of Embodiment2;

FIG. 22 is a fragmentary schematic view illustrating another variationof the configuration of the first sensing section of the first workingelectrode and the second sensing section of the second working electrodeof Embodiment 2;

FIG. 23 is a schematic sectional view taken along along line XXIII-XXIIIof FIG. 22;

FIG. 24 shows fragmentary schematic views illustrating a configurationof Embodiment 3 of the implantable micro-biosensor according to thedisclosure;

FIG. 25 is a schematic sectional view taken along line XXV-XXV of FIG.24;

FIG. 26 is a schematic sectional view taken along line XXVI-XXVI of FIG.24;

FIG. 27 shows fragmentary schematic views illustrating a variation ofthe configuration of Embodiment 3;

FIG. 28 is a schematic sectional view taken along line XXVIII-XXVIII ofFIG. 27;

FIG. 29 shows schematic views illustrating steps (a1), (a2), (a3) of aprocess for manufacturing Embodiment 3;

FIG. 30 is a schematic sectional view taken along line XXX-XXX of FIG.29 for showing the configuration of a second surface of Embodiment 3;

FIG. 31 is a schematic sectional view taken along line XXXI-XXXI of FIG.29 for showing the configuration of the second surface of Embodiment 3;

FIG. 32 shows schematic views illustrating a configuration of Embodiment4 of the implantable micro-biosensor according to the disclosure;

FIG. 33 is a schematic sectional view taken along line XXXIII-XXXIII ofFIG. 32;

FIG. 34 is a schematic sectional view taken along line XXXIV-XXXIV ofFIG. 32;

FIG. 35 is a schematic view illustrating a configuration of Embodiment 5of the implantable micro-biosensor according to the disclosure;

FIG. 36 is a circuit diagram illustrating a circuit design ofApplication Embodiment 1;

FIG. 37 is a schematic time-sequence diagram illustrating an operationtime sequence of Application Embodiment 1;

FIG. 38 is a schematic time-sequence diagram illustrating an operationtime sequence of Application Embodiment 2;

FIG. 39 is a schematic time-sequence diagram illustrating an operationtime sequence of Application Embodiment 3;

FIG. 40 is a circuit diagram illustrating a circuit design ofApplication Embodiment 4;

FIG. 41 is a circuit diagram illustrating another circuit design ofApplication Embodiment 4;

FIG. 42 is a schematic time-sequence diagram illustrating an operationtime sequence of Application Embodiment 4;

FIG. 43 is a graph plot of current signal versus time curves toillustrate the result of in vitro elimination of interference ofApplication Example 1, in which curve C1 shows current signals measuredat the first sensing section when the second working electrode isswitched on for the elimination of the interference, curve C2 showscurrent signals measured at the second sensing section when the secondworking electrode is switched on for the elimination of theinterference, and curve C3 shows current signals measured at the firstsensing section when the second working electrode is not switched on forthe elimination of the interference;

FIG. 44 is graph plot of glucose concentration versus time curve toillustrate the measurement result of glucose concentration in a bodyover the measurement time period without execution of the elimination ofthe interference, in which a portion indicated by a dashed-line framerepresents a time period of medical interference, curve (a) represents ameasurement result of the first working electrode, and a plurality ofdots (c) represent glucose concentration values measured with aconventional test strip using an analyzing instrument;

FIG. 45 is a bar chart illustrating the difference of the measurementresult of FIG. 44 under the medical interference and without the medicalinterference;

FIG. 46 is graph plot of glucose concentration versus time curves toillustrate the measurement result of glucose concentration in a bodyover the measurement time period with execution of the elimination ofthe interference, in which a portion indicated by a dashed-line framerepresents the time period of the medical interference, curve (a)represents a measurement result of the first working electrode, curve(b) represents a measurement result of the second working electrode, anda plurality of dots (c) represent glucose concentration values measuredwith a conventional test strip using an analyzing instrument; and

FIG. 47 is a bar chart illustrating the difference of the measurementresult of FIG. 46 under the medical interference and without the medicalinterference.

DETAILED DESCRIPTION

Before the disclosure is described in greater detail, it should be notedthat where considered appropriate, reference numerals or terminalportions of reference numerals have been repeated among the figures toindicate corresponding or analogous elements, which may optionally havesimilar characteristics.

The term “analyte” as used herein refers to any substance to be detectedthat exists in an organism, for example, glucose, lactose, and uricacid, but are not limited thereto. In the embodiments illustrated below,the analyte is glucose. In certain embodiments, the implantablemicro-biosensor is an implantable glucose micro-biosensor, which is usedfor detecting a concentration of glucose in an interstitial fluid of abody. The term “a biological fluid” as used herein may be, for example,the interstitial fluid, but is not limited thereto. The term “aphysiological parameter” as used herein may be, for example, aconcentration, but is not limited thereto.

The term “at least one” as used herein will be understood to include oneas well as any quantity more than one.

An implantable micro-biosensor according to the disclosure is used forcontinuously monitoring a physiological parameter of an analyte in abody, and includes a substrate, a first working electrode, at least onesecond working electrode, and at least one counter electrode.

The substrate has a first surface and a second surface opposite to thefirst surface.

The first working electrode includes a first sensing section disposed onthe first surface of the substrate. The first sensing section is drivenby a first potential difference so as to form a measuring region tomeasure a physiological signal in response to the physiologicalparameter of the analyte.

The at least one second working electrode is disposed on the firstsurface of the substrate, and includes a second sensing sectionproximate to the first sensing section. The second sensing section isdriven by a second potential difference to form aninterference-eliminating region that is in touch with a surrounding ofthe first sensing section and at least partially overlaps with themeasuring region, so as to consume an interfering substance in the bodywhich approaches the first and second sensing sections.

The at least one counter electrode is disposed on the first or secondsurface of the substrate, and includes a silver/silver halide, so as tocooperate with the first working electrode to measure the physiologicalsignal, to cooperate with the second working electrode to consume theinterfering substance, and to selectively cooperate with the first orsecond working electrode so as to be driven to regenerate silver halide.

In certain embodiments, the implantable micro-biosensor further includesa third working electrode disposed on the first or second surface of thesubstrate and proximate to the counter electrode. The counter electrodeselectively cooperates with the third working electrode so as to bedriven to regenerate silver halide.

In certain embodiments, the counter electrode and the third workingelectrode are disposed on the second surface of the substrate and arespaced apart from each other.

In certain embodiments, a surface material of the first sensing sectionincludes a first conductive material, and a surface material of thesecond sensing section includes a second conductive material differentfrom the first conductive material.

In certain embodiments, the implantable micro-biosensor further includesa chemical reagent layer which covers at least a portion of the firstconductive material of the first sensing section and which reacts withthe analyte to generate a product.

In certain embodiments, the first working electrode is driven by thefirst potential difference so as to permit the first conductive materialto have a first sensitivity that is responsive to the product. Thesecond working electrode is driven by the second potential difference soas to permit the second conductive material to have a second sensitivitythat is responsive to the product and that is smaller than the firstsensitivity.

In certain embodiments, the first conductive material may be a noblemetal, a noble metal derivative, or a combination thereof. The noblemetal may be gold, platinum, palladium, iridium, or combinationsthereof.

In certain embodiments, the first conductive material is platinum, andthe first potential difference ranges from 0.2 V to 0.8 V.

In certain embodiments, the second conductive material is carbon, andthe second potential difference ranges from 0.2 V to 0.8 V.

In certain embodiments, the second sensing section is disposed along andspaced apart from at least one side of the first sensing section by aspacing distance of up to 0.2 mm.

In certain embodiments, the second sensing section extends along and isspaced apart from at least a portion of a periphery of the first sensingsection, and a ratio of the portion of the periphery of the firstsensing section to a total periphery of the first sensing section rangesfrom 30% to 100%.

In certain embodiments, the number of the at least one second workingelectrode is two. The second sensing sections of the second workingelectrodes are disposed, respectively, along two opposite sides of thefirst sensing section of the first working electrode.

In certain embodiments, the counter electrode comprise a mixture of thesilver-silver halide and carbon.

In certain embodiments, the counter electrode at least includes a firstlayer that contains the silver/silver halide, and a second layer thatcontains a third conductive material for covering at least a portion ofthe first layer.

In certain embodiments, the implantable micro-biosensor is operatedperpendicularly to the skin of the body. The implantable micro-biosensorhas an implanting end portion with a length of up to 6 mm.

A process for continuously monitoring a physiological parameter of ananalyte in a body according to the disclosure is used for detecting thephysiological parameter of the analyte during a monitoring time periodthat includes at least one first time section for measuring the analyte,at least one second time section for consuming an interfering substancein the body, and at least one third time section for regenerating silverhalide. The process includes the steps of:

a) providing the implantable micro-biosensor as described above;

b) applying the first potential difference between the first workingelectrode and the counter electrode during the first time section topermit the first working electrode to have a potential higher than thatof the counter electrode so as to obtain the physiological signal;

c) applying the second potential difference between the second workingelectrode and the counter electrode during the second time section topermit the second working electrode to have a potential higher than thatof the counter electrode so as to consume the interfering substance; and

d) subjecting the counter electrode to be driven by a third potentialdifference so as to regenerate the silver halide.

In certain embodiments, the first and second time sections at leastpartially overlap with each other.

In certain embodiments, the first and second time sections do notoverlap with each other.

In certain embodiments, the second and third time sections at leastpartially overlap with each other.

In certain embodiments, in step a), the implantable micro-biosensorfurther includes a third working electrode disposed on the first orsecond surface of the substrate and proximate to the counter electrode.In step d), the third potential difference is applied between thecounter electrode and the third working electrode to permit the counterelectrode to have a potential higher than that of the third workingelectrode so as to regenerate the silver halide.

In certain embodiments, the first, second, and third time sections fullyoverlap with one another.

In certain embodiments, the monitoring time period includes a pluralityof the second time sections.

Adjacent two of the second time sections are separated from each otherby implementing an open circuit operation or by applying a zeropotential difference.

In certain embodiments, in step d), an amount of the silver halidepresent in the counter electrode is maintained in a safe range.

In certain embodiments, consumption of the silver halide present in thecounter electrode corresponds to the physiological signal, and the thirdpotential difference is maintained constant so as to dynamically modifyan execution time of step d) according to the consumption of the silverhalide.

In certain embodiments, the consumption of silver halide present in thecounter electrode corresponds to the physiological signal, and anexecution time of step d) is maintained constant so as to dynamicallymodify the third potential difference according to the consumption ofthe silver halide.

Electrode Configuration and Manufacturing Process of ImplantableMicro-Biosensor Embodiment 1

Referring to FIG. 1, a first surface of Embodiment 1 of an implantablemicro-biosensor according to the disclosure includes o a first signaloutput region (A) to be connected to a transmitter (not shown), a firstsensing region (C) for measuring a physiological parameter (for example,a concentration) of an analyte (for example, glucose) in a body, and afirst signal connecting region (B) for interconnecting the first signaloutput region (A) and the first sensing region (C). The implantablemicro-biosensor is operated perpendicularly to the skin of the body andis partially implanted into the body, and has an implanting end portion,which at least includes the first sensing region (C). Specifically, theimplanting end portion has a length which is sufficient to at leastreach dermis of the skin to measure a glucose concentration in theinterstitial fluid. In certain embodiments, the length of the implantingend portion is up to 6 mm. In certain embodiments, in order to haveadvantages of avoiding foreign body sensation, forming a smallerimplantation wound, reducing pain sensation, and the like, the length ofthe implanting end portion is up to 5 mm. In certain embodiments, thelength of the implanting end portion is up to 4.5 mm. In certainembodiments, the length of the implanting end portion is up to 3.5 mm.More specifically, in certain embodiments, the first sensing region (C)has a length ranging from 2 mm to 6 mm. In certain embodiments, thelength of the first sensing region (C) ranges from 2 mm to 5 mm. Incertain embodiments, the length of the first sensing region (C) rangesfrom 2 mm to 4.5 mm. In certain embodiments, the length of the firstsensing region (C) ranges from 2 mm to 3.5 mm. In certain embodiments,the first sensing region (C) has a width ranging from 0.01 mm to 0.5 mm.In certain embodiments, the width of the first sensing region (C) isless than 0.3 mm.

Referring to FIGS. 1 to 4, Embodiment 1 of the implantablemicro-biosensor according to the disclosure includes a substrate 1, afirst working electrode 2, a second working electrode 3, a counterelectrode 4, a chemical reagent layer 6 for reacting with glucose in abody to produce hydrogen peroxide, and an insulation unit 7, whichincludes a first insulation layer 71 and a second insulation layer 72.

The substrate 1 has a first surface 11 and a second surface 12 oppositeto the first surface 11. The substrate 1 may be made of any materialwhich is useful for making an electrode substrate and which hasflexibility and insulation properties. Example of the material formaking the substrate 1 may be polyester, polyimide, and the like, andcombinations thereof, but are not limited thereto.

The first working electrode 2 is disposed on the first surface 11 of thesubstrate 1, and includes a first sensing section 20 located at thefirst sensing region (C) and covered by the chemical reagent layer 6, afirst connecting section 21 located at the first signal connectingregion (B), and a first output section 22 located at the first signaloutput region (A). A surface material of the first sensing section 20 atleast includes a first conductive material 1C. The first sensing section20 is driven by a first potential difference to permit the firstconductive material 1C to react with hydrogen peroxide, which is aproduct of a reaction of the chemical reagent layer 6 with glucose, toproduce a current signal. A physiological signal in response to aglucose concentration is obtained when a ratio relationship between thevalue of the current signal and the concentration of hydrogen peroxideis achieved.

Examples of the first conductive material 1C include carbon, platinum,aluminum, gallium, gold, indium, iridium, iron, lead, magnesium, nickel,molybdenum, osmium, palladium, rhodium, silver, tin, titanium, zinc,silicon, zirconium, combinations thereof, and derivatives thereof (forexample, alloys, oxides, metal compounds, or the like). In certainembodiments, the first conductive material 1C is a noble metal, aderivative thereof, or a combination thereof.

The second working electrode 3 is disposed on the first surface 11 ofthe substrate 1, and includes a second sensing section 30, a secondconnecting section 31, and a second output section 32. The secondsensing section 30 is disposed proximate to the first sensing section 20and is located at the first sensing region (C). The second connectingsection 31 is located at the first signal connecting region (B). Thesecond output section 32 is located at the first signal output region(A). A surface material of the second sensing section 30 at leastincludes a second conductive material 2C.

The second sensing section 30 is driven by a second potential differenceto permit the second conductive material 2C to consume at least aportion of an interfering substance in the body which approaches thesecond sensing section 30. Examples of the second conductive material 2Cmay be the same as those described above for the first conductivematerial 1C.

Referring to FIG. 5, it should be understood that when the first workingelectrode 2 is driven by the first potential difference to perform anelectrochemical reaction, the first sensing section 20 cannot only forma measuring region 1S around its surface for measuring the hydrogenperoxide within the measuring region 1S, but also react with theinterfering substance in a biological fluid of the body to produce aninterfering circuit signal, which will be outputted together with thecircuit signal to cause an interference to the physiological signal.When the second working electrode 3 is driven by the second potentialdifference, an interfering substance approaching a surface of the secondsensing section 30 is consumed via an electrochemical reaction to permitthe concentration of the interfering substance to have a concentrationgradient which decreases gradually along a direction toward the surfaceof the second sensing section 30, thereby forming at least oneinterference-eliminating region 2S. Since the second sensing section 30is proximate to the first sensing section 20, theinterference-eliminating region 2S is in touch with a surrounding of thefirst sensing section 20 and can at least partially overlap with themeasuring region 1S, such that the interfering substance approaching thefirst and second sensing sections 20, 30 can be consumed simultaneously.In order to permit the interference-eliminating region 2S tosufficiently overlap with the measuring region 1S, in the first sensingregion (C), the second sensing section 30 of the second workingelectrode 3 is disposed along and spaced apart from at least one side ofthe first sensing section 20 of the first working electrode 2 by adistance of up to 0.2 mm, so as to reduce the interference caused by theinterfering substance to the measurement of the glucose concentration.In certain embodiments, the distance ranges from 0.01 mm to 0.2 mm. Incertain embodiments, the distance ranges from 0.01 mm to 0.1 mm. Incertain embodiments, the distance ranges from 0.02 mm to 0.05 mm.

Furthermore, when the second working electrode 3 is driven by the secondpotential difference, the second conductive material 2C may react withhydrogen peroxide to produce another current signal, such that some ofthe hydrogen peroxide which should be sensed by the first workingelectrode 2 so as to accurately measure the concentration of the analyteis consumed by the second working electrode 3, causing a negative affecton the accurate measurement of the concentration of the analyte.Therefore, when the first conductive material 1C of the first workingelectrode 2 is driven by the first potential difference to have a firstsensitivity in response to hydrogen peroxide and the second conductivematerial 2C of the second working electrode 3 is driven by the secondpotential difference to have a second sensitivity, the first sensitivityof the first conductive material 1C should be greater than the secondsensitivity of the second conductive material 2C. Therefore, the firstconductive material 1C is different from the second conductive material2C. In certain embodiments, the first conductive material 1C may be anoble metal, such as gold, platinum, palladium, iridium, or combinationsthereof. Desirably, the second conductive material 2C does not has anysensitivity to hydrogen peroxide and may be, but not limited to, carbon,nickel, copper and so on.

In Embodiment 1, the first conductive material 1C is platinum, the firstpotential difference ranges from 0.2 V (volt) to 0.8 V, for example, 0.4V to 0.7 V. The second conductive material 2C is carbon. The secondpotential difference ranges from 0.2 V to 0.8 V, for example, 0.4 V to0.7 V. The first potential difference may be the same as the secondpotential difference.

Referring to FIG. 6, although the first conductive material 1C is formedat all the first sensing region (C), it is available to have only aportion of the first working electrode 2 formed with the firstconductive material 1C in the first sensing region (C).

Return to FIG. 1, a second surface of Embodiment 1 of the implantablemicro-biosensor according the disclosure includes a second signal outputregion (D), a second signal connecting region (E), and a second sensingregion (F). The counter electrode 4 is disposed on the second surface 12(that is, the second surface of the implantable micro-biosensor) of thesubstrate 1, and includes a third sensing section 40 located at thesecond sensing region (F), a third connecting section 41 located at thesecond signal connecting region (E), and a third output section 42located at the second signal output region (D), so as to cooperate withthe first working electrode 2 to measure the physiological signal, andto cooperate with the second working electrode 3 to consume theinterfering substance. It should be understood that the counterelectrode 4 is not limited to be disposed on the second surface 12, andmay be disposed on the first surface 11 as long as the aforesaidcooperation thereof with each of the first and second working electrodes2, 3 can be satisfied. When the counter electrode 4 is disposed on thesecond surface 12, the width of the implantable micro-biosensor can bedecreased. In addition, the counter electrode 4 may cooperateselectively with the first working electrode 2 or the second workingelectrode 3 to regenerate silver halide.

In Embodiment 1, the material for the counter electrode 4 includes asilver/silver halide (R) so as to permit the counter electrode 4 tofunction as a reference electrode as well. That is, the counterelectrode 4 can be cooperated with the first working electrode 2 to froma loop so as to allow the electrochemical reaction occurring at thefirst working electrode 2 and to provide a stable relative potential asa reference potential. A non-limiting example of the silver halide issilver chloride, and silver iodide is also available. In view to reducethe production cost and enhance the biological compatibility of theimplantable micro-biosensor of the disclosure, the silver/silver halide(R) may be included only on the surface of the counter electrode 4. Thesilver/silver halide (R) may be blended with a carbon material (forexample, a carbon paste) in a suitable ratio as long as the counterelectrode 4 can execute the intended function.

The amount of the silver halide in the third sensing section 40 of thecounter electrode 4 should be in a safe range, so as to avoid completeconsumption of the silver halide and to permit the implantablemicro-biosensor of the disclosure to be stably maintained in a testenvironment for measuring the physiological signal. Therefore, referringto FIG. 7, in order to avoid stripping of the silver halide in theenvironment of the body, the third sensing section 40 may furtherinclude a third conductive material 3C that covers at least a portion ofthe silver/silver halide (R). The silver/silver halide (R) on the thirdsensing section 40 that is not covered by the third conductive material3C can be used for measuring the physiological signal. The term “coverat least a portion” described above refers to partially cover or fullycover. Examples of the third conductive material 3C include carbon,silver, and any other conductive materials that will not affect theintended function of the counter electrode 4.

In addition, in order to miniaturize the implantable micro-biosensor ofthe disclosure and to maintain the amount of the silver halide in a saferange, a third potential difference may be applied between the counterelectrode 4 and the first working electrode 2 or between the counterelectrode 4 and the second working electrode 3 to permit the counterelectrode 4 to have a potential higher than that of the first or secondworking electrode 2, 3, so as to regenerate the silver halide and tomaintain the silver halide at the third sensing section 40 of thecounter electrode 4 to be in a safe range. Specifically, a weight ratioof silver to silver halide may be, but is not limited to, 95 wt %: 5 wt%, 70 wt %: 30 wt %, 60 wt %: 40 wt %, 50 wt %: 50 wt %, 40 wt %: 60 wt%, 30 wt %: 70 wt %, or 5 wt %: 95 wt % based on 100 wt % of a totalweight of silver and silver halide. In other words, a weight ratio ofthe silver halide to the silver/silver halide (R) is greater than 0 andless than 1. In particular, the abovementioned weight ratio rangesbetween 0.01 and 0.99, more particularly, between 0.1 and 0.9, between0.2 and 0.8, between 0.3 and 0.7, or between 0.4 and 0.6.

As described above, the chemical reagent layer 6 covers at least aportion of the first conductive material 1C of the first sensing section20. Referring specifically to FIG. 2, in Embodiment 1, the chemicalreagent layer 6 covers not only the first sensing section 20, but alsothe second sensing section 30, a portion or whole of the clearancebetween the first and second sensing sections 20, 30, and the thirdsensing section 40. In other words, the chemical reagent layer 6 coversat least portions of the first sensing region (C) and the second sensingregion (F). The chemical reagent layer 6 includes at least one type ofenzyme which is reactive with the analyte or which can enhance areaction of the analyte with other material. Examples of the enzyme mayinclude glucose oxidase and glucose dehydrogenase, but are not limitedthereto. In the disclosure, the first and second working electrodes 2and 3 are designed such that the chemical reagent layer 6 may notinclude the mediator.

Except for exposure of the sensing regions (including the first andsecond sensing regions (C, F)) for signal-sensing and the signal outputregions (including the first and second signal output regions (A, D))for signal-outputting, it is necessary to insulate the first, second,and third signal connecting sections 21, 31, 41 in the signal connectingregions (including the first and second signal connecting regions (B,E)). Therefore, the first insulation layer 71 is located at the firstsignal connecting region (B), and covers the first connecting section 21of the first working electrode 2 and the second connecting section 31 ofthe second working electrode 3. The second insulation layer 72 islocated at the second signal connecting region (E), and covers the thirdconnecting section 41 of the counter electrode 4 on the second surface12 of the substrate 1. The second insulation layer 72 has a length whichmay be the same as or different from that of the first insulation layer71. The insulation layer unit 7 may be made of any insulation material,for example, parylene, polyimide, PDMS, LCP or SU-8 of MicroChem, and soon, but is not limited thereto. Each of the first and second insulationlayers 71, 72 may have a single-layered or multi-layered configuration.The chemical reagent layer 6 may also cover a portion of the firstinsulation layer 71 and/or the second insulation layer 72 in addition tothe first, second, and third sensing sections 20, 30, 40.

The chemical reagent layer 6, the first insulation layer 71, and thesecond insulation layer 72 may be covered with a polymer confinementlayer (not shown), so as to confine undesirable substances from enteringinto the implantable micro-biosensor which may affect the measurement ofthe analyte.

Referring specifically to FIG. 1, each of the first and second signaloutput regions (A, D) further includes a plurality of electric contactportions 8. Specifically, each of the first and second signal outputregions (A), (D) includes two of the electric contact portions 8. Two ofthe electric contact portions 8 are used as a switch set for actuating apower source of the transmitter when the transmitter is electricallyconnected to the implantable micro-biosensor. The other two of theelectric contact portions 8 are used as a mediator for datatransmission. It should be understood that the number and the functionof the electric contact portions 8 are not limited to the aforesaid.

Referring to FIGS. 8 and 9, Embodiment 1 of the implantablemicro-biosensor also can be configured with a reference electrode 9disposed on the second surface 12 of the substrate 1. The referenceelectrode 9 includes a fourth sensing section 90 located at the secondsensing region (F), a fourth connecting section 91 located at the secondsignal connecting region (E), and a fourth output section 92 located atthe second signal output region (D). Thus, the silver/silver halide (R)of the counter electrode 4 can be omitted and may be at least providedon a surface of the fourth sensing section 90.

Referring specifically to FIGS. 1 to 4, a process for manufacturingEmbodiment 1 of the implantable micro-biosensor according to thedisclosure includes the steps of:

(A) providing the substrate 1 having the first surface 11;

(B) forming the first work electrode 2 on the first surface 11 of thesubstrate 1, the first work electrode 2 at least including the firstsensing section 20 which includes the first conductive material 1C;

(C) forming the at least one second work electrode 3 on the firstsurface 11 of the substrate 1, the second work electrode 3 at leastincluding the second sensing section 30, which is disposed proximate toat least one side of the first sensing section 20 and which includes thesecond conductive material 2C different from the first conductivematerial 1C;

(D) forming the counter electrode 4 on the substrate 1 so as tocooperate with the first work electrode 2 to measure the physiologicalparameter of the analyte; and

(E) forming the chemical reagent layer 6 which at least covers the firstconductive material 1C of the first sensing section 20 so as to reactwith the analyte to generate a product.

Specifically, the first surface 11 of the substrate 1 includes the firstsignal output region (A), the first signal connecting region (B), andthe first sensing region (C). Steps B) and C) are implemented by thesub-steps of:

-   -   (a) applying the second conductive material 2C on the first        surface 11 of the substrate 1;    -   (b) subjecting the second conductive material 2C to patterning        according to predetermined sizes, positions, lengths, areas, and        the like of the first and second working electrodes 2, 3, to        divide the second conductive material 2C into a first area and        at least one second area that are separated from each other;        and (c) applying the first conductive material 1C at the first        sensing region (C) to cover at least a portion of the second        conductive material 2C at the first area to form the first        sensing section 20 of the first working electrode 2 and to        permit the second conductive material 2C at the at least one        second area to be configured as the second working electrode 3,        which includes the second signal output section 32 located at        the first signal output region (A), the second signal connecting        section 31 located at the first signal connecting region (B),        and the second sensing section 30 located at the first sensing        region (C). Therefore, both of the first and second sensing        sections 20, 30 in Embodiment 1 manufactured by the        abovementioned process are located at the first sensing region        (C).

Specifically, referring to FIGS. 10 to 12, after sub-step (b), thesecond conductive material 2C is divided into the first area and thesecond area which have stripe geometries and which are separated fromeach other. The second conductive material 2C at the second area extendsfrom the first sensing region (C) through the first signal connectingregion (B) to the first signal output region (A), as shown in FIG. 1.After sub-step (c), the first conductive material only covers the secondconductive material 2C at the first sensing region (C). Therefore,referring specifically to FIG. 11, the first sensing section 20 of thefirst working electrode 2 includes a layer of the second conductivematerial 2C disposed on the first surface 11 of the substrate 1, and alayer of the first conductive material 1C covering the layer of thesecond conducive material 2C. The first connecting section 21 of thefirst working electrode 2 only includes the layer of the secondconducive material 2C, as shown in FIG. 12. The second working electrode3 only includes the layer of the second conductive material 2C.

In a variation of Embodiment 1, the first conductive material 1C canonly cover a portion of the second conductive material 2C of the firstsensing region (C) as shown in FIG. 6 by modification of sub-step (c).

In another variation of Embodiment 1, the first conductive material 1Cmay not only cover the second conductive material 2C at the firstsensing region (C), but also extend to cover a portion of the secondconductive material 2C at the first signal connecting region (B) bymodification of sub-steps (b) and (c).

In further another variation of Embodiment 1, the second conductivematerial 2C at the first area may have a length less than that of thesecond conductive material 2C at the second area by modification ofsub-step (b). For example, the second conductive material 2C at thefirst area may be located only at the first signal output region (A) andthe first signal connecting region (B). Thereafter, the first conductivematerial 1C not only is formed at the first sensing region (C), but alsocover the second conductive material 2C at the first signal connectingregion (B) by sub-step (c), so as to permit the first sensing section 20to be connected to the first signal output section 22.

Referring to FIGS. 13 to 15, in yet another variation of Embodiment 1,the first conductive material 2C may cover whole of the secondconductive material 2C, such that each of the first sensing section 20,the first connecting section 21, and the first signal output section 22has a two-layered configuration which includes a layer of the secondconductive material 2C and a layer of the first conductive material 1Ccovering the layer of the second conductive material 2C. The secondworking electrode 3 only includes a layer of the second conductivematerial 2C, as described above. Alternatively, it should be understoodthat the first working electrode 2 may only include the first conductivematerial 1C without the second conductive material 2C.

The positions and the areas of the first signal output region (A), thefirst signal connecting region (B), and the first sensing region (C) maybe defined by an insulation layer. Therefore, in certain embodiments,sub-step (b) may be followed by a sub-step (b′) of forming the firstinsulation layer 71 on the first surface 11 of the substrate 1 so as todefine the first signal connecting region (B), at which the firstinsulation layer 71 is located, the first sensing region (C), which isnot covered by the first insulation layer 71 and which is to beimplanted under the skin of the body, and the first signal output region(A), which is not covered by the first insulation layer 71 and which isto be connected to the transmitter. At the first signal connectingregion (B), each of the first connecting section 21 of the first workingelectrode 2 and the second connecting section 31 of the second workingelectrode 3 has a layered configuration which at least includes a layerof the second conducive material 2C.

In certain embodiment, sub-step (b) is performed to allow the secondsensing section 30 to be spaced apart from the at least one side of thefirst sensing section 20 by a distance of up to 0.2 mm.

In certain embodiments, sub-step (a) is implemented by a screen printingprocess. Sub-step (b) is implemented by an etching process, andpreferably a laser engraving process. Sub-step (d) is implemented with aconductive material by a sputtering process, but preferably a platingprocess.

Step (E) is implemented by immersing the substrate 1 formed with thefirst working electrode 2, the second working electrodes 3 and thecounter electrode 4 into a solution containing the chemical reagent, soas to permit the first conductive material 1C of the first sensingsection 20, the second conductive material 2C of the second sensingsection 30 and the third sensing section 40 of the counter electrode 4to be covered simultaneously with the chemical agent.

In certain embodiments, before step (E), step (D′) is implemented byforming a third electrode (not shown) on the substrate 1. The thirdelectrode is spaced apart from the counter electrode 4 and the firstworking electrode 2, and may be a reference electrode or a third workingelectrode.

In certain embodiments, step (E) may be followed by step (D″) of formingthe second insulation layer 72 on the second surface 12 of the substrate1, so as to define the second sensing region (F) on the second surface12 of the substrate 1.

It should be understood that the process for manufacturing Embodiment 1of the implantable micro-biosensor according to the disclosure is notlimited to the aforesaid steps, sub-steps, and order, and that the orderof the aforesaid steps and sub-steps may be adjusted according topractical requirements.

In the process for manufacturing Embodiment 1 of the implantablemicro-biosensor according to the disclosure, two sensing sections havingdifferent materials on the surfaces thereof may be formed on a samesensing region, such that the sensing sections can be coveredsimultaneously with a same chemical agent layer so as to simplify theconventional process. In addition, the geometries and sizes of the firstand second working electrodes 2, 3, and the clearance between the firstand second working electrodes 2, 3, and the like, can be controlledprecisely by the patterning process. Furthermore, the processingperformed on the second surface 12 of the substrate 1 may be modifiedaccording to practical requirements.

Embodiment 2

Referring to FIGS. 16 to 19, Embodiment 2 of the implantablemicro-biosensor according to the disclosure is substantially similar toEmbodiment 1 except for the following differences.

In order to effectively reduce the interference of the interferingsubstance on the measurement of the physiological signal so as to be inan acceptable error range, in Embodiment 2, the second sensing section30 is disposed along and spaced apart from at least three sides of thefirst sensing section 20 by a distance. In other words, the at leastthree sides of the first sensing section 20 are surrounded by and spacedapart from the second sensing section 30 by the distance. In certainembodiments, the distance is up to 0.2 mm. In certain embodiments, thedistance ranges from 0.02 mm to 0.05 mm. Specifically, the secondsensing section 30 is disposed in a U-shaped geometry along and spacedapart from the at least three sides of the first sensing section 20.Therefore, referring to FIG. 20, the second sensing section 30 forms atleast two of the interference-eliminating regions 2S, which are locatedat two opposite sides of the first sensing section 20, and which overlapwith the measuring region 1S, so as to not only consume the interferingsubstance approaching the second sensing section 30 but also consume theinterfering substance within the first sensing section 20. In certainembodiments, the acceptable error range of the interference is up to20%, for example, up to 10%.

A process for manufacturing Embodiment 2 is substantially similar tothat for manufacturing Embodiment 1 except for the followingdifferences.

In sub-step (b), the second conductive material 2C is patterned topermit the second conductive material 2C at the second area to be formedas a U-shaped geometry and to surround the second conductive material 2Cat the first area. Therefore, the geometry of the second sensing section30 and the extension of the second sensing section 30 to surround thefirst sensing section 20 may be modified by patterning the secondconductive material 2C.

In addition, in other variations of Embodiment 2, the first and secondsensing sections 20, 30 may be positioned as shown in FIG. 21(a) andFIG. 21(b). In other words, when the second sensing section 30 extendsalong and is spaced part from at least a portion of a periphery of thefirst sensing section 20, a ratio of the portion of the periphery of thefirst sensing section 20 to a total periphery of the first sensingsection 20 ranges from 30% to 100%, such that the second sensing section30 may be configured as an I-shaped (as illustrated in Embodiment 1),L-shaped, or U-shaped geometry.

Referring to FIGS. 22 and 23, in yet another variation of Embodiment 2,the second sensing section 30 may extend along and is spaced apart fromwhole of the periphery of the first sensing section 20. Specifically,the first connecting section 21 and the first output section 22 aredisposed on the second surface 12 of the substrate 1. The first sensingsection 20 includes a first portion disposed on the first surface 11 ofthe substrate 1, a second portion disposed on the second surface 12 ofthe substrate 1 and extending toward the first connecting section 21,and a middle portion extending through the substrate 1 to interconnectthe first and second portions.

Embodiment 3

Referring to FIGS. 24 to 26, Embodiment 3 of the implantablemicro-biosensor according to the disclosure is substantially similar toEmbodiment 2 except for the following differences.

In Embodiment 3, the implantable micro-biosensor further includes areference electrode 9 disposed on the second surface 12 of the substrate1 and spaced from the counter electrode 4. A surface material of thereference electrode 9 at least includes the silver/silver halide (R).The reference electrode 9 has an area less than that of the counterelectrode 4, so as to provide a sufficient capacity and to adjust theamount of the silver/silver halide (R).

Specifically, the counter electrode 4 is disposed on the second surface12 of the substrate 1, and the third sensing section 40 of the counterelectrode 4 includes a front portion 40 a extending longitudinally alongthe second sensing region (F) and a rear portion 40 b extendinglongitudinally toward a direction away from the second sensing region(F). In Embodiment 3, the third sensing section 40 of the counterelectrode 4 is composed of the front and rear portions 40 a, 40 b.

The reference electrode 9 is spaced apart from the counter electrode 4,and includes the fourth sensing section 90 located at the second sensingregion (F). The fourth sensing section 90 has an area less than that ofthe third sensing section 40. Specifically, the front and rear portions40 a, 40 b of the third sensing section 40 are disposed proximate to twoadjacent sides of the fourth sensing section 90 of the referenceelectrode 9 to permit the counter electrode 4 to be configured as anL-shaped geometry. A total of the widths of the fourth sensing section90 and the rear portion 40 b of the counter electrode 4 is less thanthat of the front portion 40 a of the counter electrode 4. In addition,the first and second insulation layers 71, 72 may have same lengths.Referring specifically to FIG. 26, the chemical reagent layer 6 maycover the first, second, third, and fourth sensing sections 20, 30, 40,90.

Referring to FIGS. 27 and 28, in a variation of Embodiment 3, the firstand second insulation layers have different lengths such that the firstsensing region (C) has a length less than that of the second sensingregion (F). Therefore, the chemical reagent layer 6 only covers thefirst sensing section 20, the second sensing section 30, and the frontportion 40 a of the counter electrode 4. The fourth sensing section 90of the reference electrode 9 may not be covered with the chemicalreagent layer 6.

In another variation of Embodiment 3, at least a portion of thesilver/silver halide (R) on the fourth sensing section 90 of thereference electrode 9 may be covered by the third conductive material3C, so as to decrease the exposure area of the silver halide, therebyreducing the possibility of the silver halide being lost due todissociation. Therefore, the side edge and/or the surface of thereference electrode 9 which is not covered by the third conductivematerial 3C may cooperate with the first working electrode 2 and thecounter electrode 4 to conduct the measurement. In certain embodiments,the third conductive material 3C is carbon.

A process for manufacturing Embodiment 3 of the implantablemicro-biosensor according to the disclosure is substantially similar tothe process for manufacturing Embodiment 2 except for the followingdifferences.

In step (D), the counter electrode 4 is formed on the second surface 12of the substrate 1, and includes the third sensing section 40 located atthe second sensing region (F). The third sensing section 40 includes thefront portion 40 a and the rear portion 40 b. In step (D′), thereference electrode 9 is formed on the second surface 12 of thesubstrate 1, and is spaced apart from the counter electrode 4. Thereference electrode 9 includes the fourth sensing section 90 located atthe second sensing region (F).

It is noted that, before the micro-biosensor is ready for shipping outof the plant for sale, the counter electrode 4 of Embodiment 1 or 2, orthe reference electrode 9 of Embodiment 3 can have no silver halide(that is, the initial amount of the silver halide can be zero) butsilver. An initial amount of the silver halide can be generated on thecounter electrode 4 or the reference electrode 9 by oxidizing the silvercoated on the counter electrode 4 or the reference electrode 9 during avery first replenishment period after the micro-biosensor is implantedsubcutaneously into the patient and before a first measurement isproceeded. In such case, the silver is oxidized to silver ion thus to becombined with chloride ion in the body fluid to form the silver halide.The measurement can be performed after a predetermined ratio betweensilver and silver halide is reached.

Accordingly, referring to FIG. 29, in a first process for manufacturingEmbodiment 3 of the implantable micro-biosensor, steps (D) and (D′) areimplemented by the sub-steps of: (a1) forming a backing material layer(L) on the second surface 12 of the substrate 1; and (a2) applying areference electrode material (for example, silver-silver halide) or aprecursor material (P) (for example, silver) of the reference electrodematerial on a portion of the backing material layer (L); (a3) subjectingthe backing material layer (L) and the reference electrode material orthe precursor material (P) to patterning so as to define a third areaand a fourth area which are separated from each other and which are notconnected electrically to each other, the backing material layer (L) atthe third area being configured as the counter electrode 4.

Specifically, the active area of the counter electrode 4 and thereference electrode 9, the cooperated configuration between the abovetwo, the location or size of the silver-silver halide on the surface ofthe electrode can be easily controlled through sub-step (a2) so as tocomplete the manufacture of the counter electrode 4 and the referenceelectrode 9 and control the amount of the silver-silver halide.

Specifically, the backing material layer (L) located at the third areahas a different width along a longitudinal direction of the third area.A front portion of the backing material layer (L) having a greater widthis used for forming the front portion 40 a of the third sensing section40 of the counter electrode 4, and a rear portion of the backingmaterial layer (L) having a smaller width is used for forming the rearportion 40 b of the third sensing section 40 of the counter electrode 4.A portion or whole of the reference electrode material or the precursormaterial (P) is located at the fourth area. If the reference electrodematerial is applied in sub-step (a2), the fourth sensing section 90 ofthe reference electrode 9 is formed directly thereby. Alternatively, ifthe precursor material (P) is applied in sub-step (a2), an additionalsub-step (a4) is implemented to convert the precursor material (P) atthe fourth area to the reference electrode material to form the fourthsensing section 90 of the reference electrode 9. Referring specificallyto FIGS. 30 and 31, the rear portion 40 b of the third sensing section40 of the counter electrode 4 is formed as a laminated configurationwhich includes the backing material layer (L) and a layer of theprecursor material (P) covering the backing material layer (L). Thefourth sensing section 90 of the reference electrode 9 is formed as alaminated configuration which includes the backing material layer (L)and a layer of the silver/silver halide (R) covering the backingmaterial layer (L). The front portion 40 a of the third sensing section40 of the counter electrode 4 is formed as a single-layeredconfiguration made of the backing material layer (L). In Embodiment 3, aportion of the precursor material (P) is located at the fourth area, anda remaining portion of the precursor material (P) is located at thethird area. In another variation of Embodiment 3, in sub-step (a3),whole of the precursor material (P) may be located at the fourth area.

In a second process for manufacturing Embodiment 3 of the implantablemicro-biosensor, steps (D) and (D′) are implemented by the sub-steps of:

(b1) forming the backing material layer (L) on the second surface 12 ofthe substrate 1;

(b2) subjecting the backing material layer (L) to patterning to define athird area and a fourth area which are separated from each other andwhich are not connected electrically to each other, the backing materiallayer (L) at the third area being configured as the counter electrode 4;and

(b3) applying the reference electrode material or the precursor material(P) of the reference electrode material to at least a portion of thefourth area, so as to permit the fourth area to be configured as thereference electrode 9.

If the reference electrode material is applied in sub-step (b3), thefourth sensing section 90 of the reference electrode 9 is formeddirectly thereby.

Alternatively, if the precursor material (P) is applied in sub-step(b3), an additional sub-step (a4) is implemented to convert theprecursor material (P) at the fourth area to the reference electrodematerial to form the fourth sensing section 90 of the referenceelectrode 9.

In certain embodiments, the backing material layer (L) may be formed asa single-layered configuration or a multi-layered configuration, each ofwhich is made from carbon, silver, or a combination thereof.Specifically, the backing material layer (L) may be formed as asingle-layered configuration made of carbon, such that the third sensingsection 40 of the counter electrode 4 is configured as a carbon layer.Alternatively, the backing material layer (L) may be formed as atwo-layered configuration, which includes a silver layer disposed on thesecond surface of the substrate 1 and a carbon layer disposed on thesilver layer.

Embodiment 4

Referring to FIGS. 32 to 34, Embodiment 4 of the implantablemicro-biosensor according to the disclosure is substantially similar toEmbodiment 3 except for the following differences.

In Embodiment 4, the counter electrode 4 also functions as a referenceelectrode, and the reference electrode 9 in Embodiment 2 is replacedwith a third working electrode 5. The material and configuration for thethird working electrode 5 may be the same as those described above forthe first working electrode 2 or the second working electrode 3.Specifically, the configuration of the third working electrode 5 inEmbodiment 4 is the same as that of the first working electrode 2 inEmbodiment 1, and includes a carbon layer and a platinum layer disposedon the carbon layer. In certain embodiments, the third working electrode5 may be disposed on the first surface 11 of the substrate 1. In otherwords, the third working electrode 5 and the counter electrode 4 may bedisposed on the same surface or different surfaces of the substrate 1.In addition, the configuration of the third working electrode 5 is notlimited to Embodiment 4 and can be arranged as Embodiment 1 shown inFIG. 8, that is, the length, area and even shape of the third workingelectrode 5 can be the same as the counter electrode 4.

Referring specifically to FIGS. 33 and 34, a process for manufacturingEmbodiment 4 of the implantable micro-biosensor according to thedisclosure is substantially similar to the process for manufacturingEmbodiment 3 except for the following differences.

In the process for manufacturing Embodiment 4, in step (D′), the thirdworking electrode 5 is formed on the second surface 12 of the substrate1, and is spaced apart from the counter electrode 4. The third workingelectrode 5 includes a fourth sensing section 50 located at the secondsensing region (F). The fourth sensing section 50 is parallel to therear portion 40 b of the third sensing section 40, and is spaced apartfrom the front portion 40 a of the third sensing section 40 along alongitudinal direction of the counter electrode 4. In other words, thecounter electrode is configured as an L-shaped geometry, such that thethird sensing section 40 of the counter electrode is spaced part fromthe fourth sensing section 50 of the third working electrode 5.

In certain embodiments, step (D) is implemented by the sub-steps of:

(c1) forming a backing material layer (L) on the second surface 12 ofthe substrate 1;

(c2) defining on the second surface 12 of the substrate 1, a third areaand a fourth area which are separated from each other, the third areabeing used for the counter electrode 4, and the backing material layer(L) located at the third area has a different width along a longitudinaldirection of the third area. A front portion of the backing materiallayer (L) having a greater width is used for forming the front portion40 a of the third sensing section 40 of the counter electrode 4, and arear portion of the backing material layer (L) having a smaller width isused for forming the rear portion 40 b of the third sensing section 40of the counter electrode 4; and

(c3) applying the reference electrode material (for example,silver-silver halide) or the precursor material (P) (for example,silver) of the reference electrode material on at least a portion of thebacking material layer (L) at the third area, and specifically, at thefront portion 40 a of the third sensing section 40.

If the precursor material (P) is applied in sub-step (c3), an additionalsub-step (c4) is implemented to convert the precursor material (P) tothe reference electrode material, so as to permit the front portion 40 aof the counter electrode 4 to be used as the third sensing section 40and to function as a reference electrode as well.

In certain embodiments, in sub-step (c1), the backing material layer (L)may be formed as a single-layered configuration or a multi-layeredconfiguration, each of which is made from carbon, silver, or acombination thereof.

It should be understood that the counter electrode 4 may be formed as asingle-, double-, or triple-layered configuration. The counter electrode4 formed as a double-layered configuration may include a conductivematerial layer (for example, a carbon layer, but is not limited thereto)disposed on the substrate 1, and a layer of the silver/silver halide (R)covering the conductive material layer. The conductive material layer isprovided to avoid impedance problem due to excessive halogenation ofsilver in sub-step (c4) or the abovementioned initial halogenation step.

When the conductive material layer is a carbon layer, another conductivematerial layer (for example, a silver layer) may be disposed between thesecond surface 12 of the substrate 1 and the conductive material layerto permit the counter electrode 4 to be formed as a triple-layeredconfiguration, so as to reduce the high impedance problem which mayoccur at the second signal output region (D) when the carbon layer isdisposed directly on the second surface 12 of the substrate 1.

In certain embodiments, the counter electrode 4 may be formed as asingle-layered configuration. Therefore, the backing material layer (L)in sub-step (c1) may be made from the silver/silver halide, a mixture ofthe silver/silver halide and a conductive material (for example,carbon), or a mixture of silver and the conductive material (forexample, carbon), and sub-step (c3) may be omitted. The counterelectrode 4 is thus formed as a single-layered configuration includingsilver/silver halide or the mixture of the silver/silver halide and theconductive material (for example, carbon). The amount of thesilver/silver halide present in the counter electrode 4 is notspecifically limited as long as the counter electrode 4 executes theintended operation. Formation of the counter electrode 4 using themixture of the silver/silver halide and the conductive material mayalleviate the insulation problem during halogenation, the adhesionproblem during lamination, and the high impedance problem of the secondsignal output region (D).

Similarly, in Embodiment 4, the first working electrode 2 is used formeasuring the physiological signal, and the second working electrode 3is used to reduce the interference of the interfering substance in thebody to the measurement. However, regeneration of silver halide iscarried out by cooperation of the third working electrode 5 with thecounter electrode 4. Specifically, the third potential difference isapplied between the counter electrode 4 and the third working electrode5 to permit the counter electrode 4 to have a potential higher than thatof the third working electrode 5, so as to permit the counter electrode4 to perform an oxidation reaction to regenerate the silver halide,thereby enhancing the efficiency of the measurement, the consumption ofthe interference, and the regeneration of silver halide.

Embodiment 5

Referring to FIG. 35, Embodiment 5 of the implantable micro-biosensoraccording to the disclosure is substantially similar to Embodiment 1except for the following differences.

In Embodiment 5, two of the second working electrodes 3, 3′ areincluded. Similar to the second working electrode 3 described above, thesecond working electrode 3′ includes a second sensing section 30′, asecond connecting section 31′, and a second output section 32′. Thesecond sensing sections 30, 30′ of the second working electrodes 3, 3′may have the same or different lengths and/or areas. A distance betweenone of the two second sensing sections 30, 30′ and the first sensingsection 20 may be different from that between the other one of the twosecond sensing sections 30, 30′ and the first sensing section 20.

A process for manufacturing Embodiment 5 of the implantablemicro-biosensor according to the disclosure is substantially similar tothe process for manufacturing Embodiment 1 except for the followingdifferences.

In the process for manufacturing Embodiment 5 of the implantablemicro-biosensor according to the disclosure, in sub-step (b), two of thesecond areas are formed to define the two second working electrodes 3,3′, and the two second sensing sections 30, 30′ of the two secondworking electrodes 3, 3′ are disposed, respectively, along two oppositesides of the first sensing section 20 of the first working electrode 2.

Operation Procedures of Implantable Micro-Biosensor ApplicationEmbodiment 1

Embodiment 4 of the implantable micro-biosensor according to thedisclosure is used in Application Embodiment 1, and includes thesubstrate 1, the first working electrode 2, the second working electrode3, the counter electrode 4, the third working electrode 5, and thechemical reagent layer 6. The first sensing section 20 of the firstworking electrode 2 includes a carbon layer, and a platinum layercovering the carbon layer. The second sensing section 30 of the secondworking electrode 3 is formed as a U-shaped geometry and surroundsaround the first sensing section 20, and includes a carbon layer. Thethird sensing section 40 of the counter electrode 4 includes a carbonlayer and a silver/silver chloride layer covering the carbon layer. Thefourth sensing section 50 of the third working electrode 5 has aconfiguration which is the same as that of the first sensing section 20of the first working electrode 2. The chemical reagent layer 6 coversthe first, second, third, fourth sensing sections 20, 30, 40, 50.

Referring to FIGS. 36 to 39, Embodiment 4 of the the implantablemicro-biosensor according to the disclosure is used for detecting aphysiological parameter (for example, a concentration) of an analyte(for example, glucose) in a body during a detecting time period (T) thatincludes at least one first time section (T1) for measuring the analyte,at least one second time section (T2) for consuming an interferingsubstance in the body, and at least one third time section (T3) forregenerating silver chloride.

During the first time section (T1), switch S1 is switched to aclose-circuit state and the first potential difference (for example, 0.5V, but is not limited thereto) is applied between the first workingelectrode 2 and the counter electrode 4 to permit the first workingelectrode 2 to have a potential V1 higher than a potential V4 of thecounter electrode 4, so as to permit the first working electrode 2 toperform the aforesaid oxidation reaction and to perform theelectrochemical reaction with the chemical reagent layer 6 and theanalyte to obtain the physiological signal (i1). At the same time, thecounter electrode 4 carries out a reduction reaction to reduce silverchloride to silver according to an equation below.

2AgCl+2e ⁻→2Ag+2Cl⁻

In addition, a value of the first time section (T1) can be a constant,such as 2.5 seconds, 5 seconds, 15 seconds, 30 seconds, 1 minute, 2.5minutes, 5 minutes, 10 minutes or 30 minutes. Preferably, the value ofthe first time section (T1) is 30 seconds.

During the second time section (T2), switch S2 is switched to aclose-circuit state and the second potential difference (for example,0.5 V, but is not limited thereto) is applied between the second workingelectrode 3 and the counter electrode 4 to permit the second workingelectrode 3 to have a potential V2 higher than the potential V4 of thecounter electrode 4, so as to permit the second working electrode 3 toperform a reaction on the surface thereof, thereby consuming theinterfering substance.

During the third time section (T3), switch S3 is switched to aclose-circuit state and the third potential difference is appliedbetween the counter electrode 4 and the third working electrode 5 topermit the potential V4 of the counter electrode 4 to be higher than apotential V3 of the third working electrode 5, so as to permit thecounter electrode 4 to perform an oxidation reaction, therebyregenerating the silver chloride by oxidizing silver to silver ions,which is then combine with chloride ions in the biological fluid to formsilver chloride.

The steps of obtaining the physiological signal, consuming theinterfering substance, and regenerating the silver chloride may beimplemented simultaneously or separately by proper arrangement of thepotentials V1, V2, V3, V4 of the first, second, and third workingelectrodes 2, 3, 5 and the counter electrode 4, proper arrangement ofthe first, second, and third potential differences, and proper switchingof switches S1, S2, S3. In other words, the first, second, and thirdtime sections (T1, T2, T3) my partially or fully overlap with oneanother, or are free from overlapping with one another. In addition,each of the first, second, and third time sections (T1, T2, T3) may be aconstant or variable time period.

Specifically, referring to FIGS. 36 and 37, the horizontal and verticalaxles of the figures respectively represent time and current, in whichthe line of the measurement action shows the application and remove ofthe first potential difference, another line of the interferenceeliminating action shows the application and remove of the secondpotential difference, and further another line of the silver chlorideregeneration action shows the application and remove of the thirdpotential difference. The detecting time period (T) in ApplicationEmbodiment 1 includes five of the first time sections (T1), one of thesecond time section (T2), and four of the third time sections (T3).During the whole of the detecting time period (T), switch S2 is switchedto a close-circuit state and the potential V2 of the second workingelectrode 3 is permitted to be higher than the potential V4 of thecounter electrode 4, so as to permit the second working electrode 3 toperform consumption of the interference. During the detecting timeperiod (T), switch S1 is switched cyclically and alternately between anopen-circuit state and a close-circuit state, so as to permit the firstworking electrode 2 to cooperate intermittently with the counterelectrode 4 to carry out the measurement of the analyte. Adjacent two ofthe first time sections (T1) may be separated from each other byimplementing an open circuit operation or by applying a zero potentialdifference.

In addition, during a time interval (i.e., a corresponding one of thethird time sections (T3)) between two adjacent ones of the first timesections (T1), the counter electrode 4 cooperates with the third workingelectrode 5 to execute the regeneration of the silver chloride. In otherwords, the first time sections (T1) and the third time sections (T3) donot overlap with each other.

Application Embodiment 2

Referring to FIG. 38, the operation procedures for ApplicationEmbodiment 2 are substantially similar to those of ApplicationEmbodiment 1 except for the following differences.

In Application Embodiment 2, the detecting time period (T) includes fiveof the first time section (T1), six of the second time sections (T2),and two of the third time sections (T3). The first time sections (T1)and the second time sections (T2) do not overlap with each other. Thatis to say, when the first working electrode 2 performs the measurementof the analyte during the first time sections (T1), the second workingelectrode 3 can be operated by implementing an open circuit or bygrounding. In addition, the silver chloride regeneration action can beperformed after several measurement actions or interference eliminatingactions. For example, the two third time sections (T3) in ApplicationEmbodiment 2 only overlap with two of the second time sections (T2).That is to say, the silver chloride regeneration action is performedafter two measurement actions and three interference eliminatingactions. In addition, the first interference eliminating action may becarried out prior to the first measurement action so as to effectivelyavoid the interference of the interfering substance in the body to themeasurement.

Application Embodiment 3

Referring to FIG. 39, the operation procedures for ApplicationEmbodiment 3 are substantially similar to those of ApplicationEmbodiment 1 except for the following differences.

In Application Embodiment 3, the detecting time period (T) includes fiveof the first time sections (T1), six of the second time sections (T2),and five of the third time sections (T3). The first time sections (T1)and the second time sections (T2) partially overlap with each other. Thesecond time sections (T2) and the third time sections (T3) partiallyoverlap with each other. The first time sections (T1) and the third timesections (T3) do not overlap with each other. Similarly, the firstinterference eliminating action may be carried out prior to the firstmeasurement action so as to effectively avoid the interference of theinterfering substance to the measurement. Regeneration of the silverchloride may be performed during a time interval between two adjacentones of the first time sections (T1), so as to permit an amount ofsilver halide present in the third sensing section 40 of the counterelectrode 4 to be maintained in a safe range.

Application Embodiment 4

The procedures for Application Embodiment 4 are substantially similar tothose of Application Embodiment 1 except for the following differences.

In Application Embodiment 4, Embodiment 2 of the implantablemicro-biosensor according to the disclosure is used, and includes thesubstrate 1, the first working electrode 2, the second working electrode3, the counter electrode 4, and the chemical reagent layer 6. The firstsensing section 20 of the first working electrode 2 includes a carbonlayer and a platinum layer covering the carbon layer. The second sensingsection 30 of the second working electrode surrounds 3 is formed as aU-shaped geometry and surrounds the first sensing section 20, andincludes a carbon layer. The third sensing section 40 of the counterelectrode 4 includes a carbon layer and a silver/silver chloride layercovering the carbon layer. The chemical reagent layer 6 covers thefirst, second, and third sensing sections 20, 30, 40. Specifically, thethird working electrode 5 is not included in Embodiment 2 of theimplantable micro-biosensor.

Referring to FIG. 40, the consumption of the interference is executed byapplying the second potential difference between the second workingelectrode 3 and the counter electrode 4 to permit the potential V2 ofthe second working electrode 3 to be higher than the potential V4 of thecounter electrode 4, and to permit the second working electrode 3 toperform an oxidation reaction to consume the interfering substance.

Regeneration of the silver chloride is executed by applying the thirdpotential difference between the counter electrode 4 and the secondworking electrode 3 to permit the potential V4 of the counter electrode4 to be higher than the potential V2 of the second working electrode 3,and to permit the counter electrode 4 to function as a working electrodeto perform the oxidation reaction so as to regenerate silver chloride.Specifically, switch S2 may be selectively connected to a relativelyhigh potential (i.e., a potential higher than the potential V4 of thecounter electrode 4) to allow the second working electrode 3 to executethe consumption of the interference, or a relatively low potential(i.e., a potential lower than the potential V4 of the counter electrode4) to allow the second working electrode 3 to execute the regenerationof silver chloride.

Alternatively, referring specifically to FIG. 41, the second workingelectrode 3 having the potential V2 is connected to a control unit (U)so as to adjust the amount of the thus regenerated silver chlorideobtained by each of the regenerations of the silver chloride. Forexample, the consumption amount of silver chloride present in thecounter electrode 4 corresponds to the physiological signal. When thethird potential difference is constant, an execution time of step d)(i.e., a step of regeneration of the silver chloride) is dynamicallymodified according to the consumption amount of the silver halide. Whenthe execution time of step d) is constant, the third potentialdifference is dynamically modified according to the consumption amountof the silver halide.

Referring specifically to FIG. 42, the detecting time period (T)includes five of the first time sections (T1), five of the second timesections (T2), and four of the third time sections (T3). The firstworking electrode 2 executes the measurement of the analyteintermittently during the detecting time period (T). The measurementexecuted by the first working electrode 2 and the consumption of theinterference executed by the second working electrode 3 are implementedsimultaneously. In other words, the first time sections (T1) fullyoverlap with the second time sections (T2), so as to reduce theinterference of the interfering substance to the measurement of theanalyte. When the measurement executed by the first working electrode 2and the consumption of the interference executed by the second workingelectrode 3 are paused, the second working electrode 3 cooperates withthe counter electrode 4 to execute the regeneration of the silverchloride. In other words, the third time sections (T3) do not overlapwith the first time sections (T1) and the second time sections (T2). Thesecond working electrode 3 in Application Embodiment 4 has twofunctions. Specifically, the second working electrode 3 not onlycooperates with the counter electrode 4 to execute the consumption ofthe interference during the second time sections (T2), but alsocooperates with the counter electrode 4 to execute the regeneration ofthe silver chloride during the third time sections (T3).

Application Embodiment 5

The operation procedures for Application Embodiment 5 are substantiallysimilar to those of Application Embodiment 4 except for the followingdifferences.

In Application Embodiment 5, regeneration of the silver chloride isexecuted by applying the third potential difference between the counterelectrode 4 and the first working electrode 2 to permit the potential V4of the counter electrode 4 to be higher than the potential V1 of thefirst working electrode 2. Specifically, the first working electrode 2in Application Embodiment 5 may not only cooperate with the counterelectrode 4 to consume the interference during the second time sections(T2), but also cooperate with the counter electrode 4 to regenerate thesilver halide during the second time sections (T3). That is, the firstworking electrode 2 has two functions herein.

Referring specifically to FIG. 36, in a variation of ApplicationEmbodiment 1, during the detecting time period (T), switch S1 ismaintained in a close-circuit state, so as to permit the first workingelectrode 2 to cooperate with the counter electrode 4 to execute themeasurement of the analyte, and switch S2 is switched cyclically andalternately between an open-circuit state and a close-circuit state, soas to permit the second working electrode 3 to cooperate intermittentlywith the counter electrode 4 to execute the consumption of theinterference. In addition, in certain embodiments, the first timesection (T1) may not overlap with the second time sections (T2), andsecond time sections (T2) may partially overlap with the third timesections (T3).

Application Example 1: In Vitro Elimination of the Interference

The in vitro elimination of the interference was carried out using theEmbodiment 4 of the implantable micro-biosensor according to theoperation procedures of Application Embodiment 1. The interference to beconsumed was acetaminophen.

Referring to FIG. 43, during difference time periods (Pi to PQ), theimplantable micro-biosensor was immersed sequentially in a phosphatebuffered saline solution, a 40 mg/dL glucose solution, a 100 mg/dLglucose solution, a 300 mg/dL glucose solution, a 500 mg/dL glucosesolution, a 100 mg/dL glucose solution, a 100 mg/dL glucose solutionblended with 2.5 mg/dL acetaminophen, a 100 mg/dL glucose solution, anda 100 mg/dL glucose solution blended with 5 mg/dL acetaminophen. Theresults are shown in FIG. 43, in which curve 1 represents the currentsignal measured by the first sensing section 20 when the second workingelectrode 3 did not execute the interference consumption, curve 2represents the current signal measured by the first sensing section 20while the second working electrode 3 executes the consumption of theinterference, and curve 3 represents the current signal measured by thesecond sensing section 30 while the second working electrode 3 executesthe consumption n of the interference.

As shown by curve 3 in FIG. 43, the first sensing section 20 does notmeasure a current signal in the phosphate buffered saline solution. Whenthe concentration of the glucose solution is increased, the currentsignal measured by the first sensing section 20 is increasedaccordingly. However, compared to the current signal measured by thefirst sensing section 20 during the time period P3, the current signalmeasured by the first sensing section 20 in the 100 mg/dL glucosesolution blended with 2.5 mg/dL acetaminophen during the time period P7is higher, indicating that the measured current signal during the timeperiod P7 is interfered by acetaminophen. Furthermore, the currentsignal measured by the first sensing section 20 in the 100 mg/dL glucosesolution blended with 5 mg/dL acetaminophen during the time period P9 iseven higher, indicating that the measured current signal during the timeperiod P9 is significantly interfered by acetaminophen.

Contrarily, as shown by curve C1 and curve C2 in FIG. 43, when theimplantable micro-biosensor was immersed in the 100 mg/dL glucosesolution blended with 2.5 mg/dL acetaminophen during the time period P7,the current signal measured by the first sensing section 20 issubstantially the same as that measured during the time period P3,indicating that the current signal measured by the first sensing section20 is not interfered by acetaminophen when the second working electrode3 is switched to execute the consumption of the interference. Inaddition, the second sensing section 30 of the second working electrode3 is used for oxidizing acetaminophen so as to consume acetaminophen.Therefore, no current signal is detected by the second sensing section30 in the phosphate buffered saline solution and the glucose solutionswithout acetaminophen, and a current signal measured by the secondsensing section 30 is present in the glucose solutions containingacetaminophen. It is indicated that when a measurement environment (i.e.the measuring region) contains acetaminophen, the acetaminophen can beconsumed by the second sensing section 30, such that the glucosemeasurement executed by the first sensing section 20 is not interferedby acetaminophen. Therefore, the implantable micro-biosensor of thedisclosure can be used for accurately monitoring a physiologicalparameter of an analyte.

Application Example 2: In Vivo Elimination of the Interference

The in vivo elimination of the interference was carried out usingEmbodiment 4 of the implantable micro-biosensor according to theoperation procedures of Application Embodiment 1. The interference to beconsumed was acetaminophen (i.e., medical interference). The implantablemicro-biosensor cooperates with a base and a transmitter to constitute acontinuous glucose monitoring system. The implantable micro-biosensor ishold on to the skin of a subject by the carrier and is partiallyimplanted under the skin to measure a physiological signal in responseto a glucose concentration. The transmitter is combined with the baseand is connected to the implantable micro-biosensor so as to receive andprocess the physiological signal measured by the implantablemicro-biosensor. The subject took two tablets of Panadol®(acetaminophen, 500 mg), and a time period of medical interferenceranges from 4 to 6 hours after taking the tablets. The results are shownin FIGS. 44 to 47.

FIG. 44 is graph plot of a glucose concentration versus time curve toillustrate the measurement result of the glucose concentration in asubject over the measurement time period without consumption of theinterference, in which a portion indicate by a dashed-line framerepresents a time period of medical interference, curve (a) represents ameasurement result of the first working electrode 2, and a plurality ofdots (c) represent glucose concentration values measured with aconventional test strip using an analyzing instrument. FIG. 45 is a barchart illustrating the difference of the measurement result of FIG. 44under the medical interference and without the medicine interference.FIG. 46 is graph plot of a glucose concentration versus time curves toillustrate the measurement result of the glucose concentration in thesubject over the measurement time period with consumption of theinterference, in which a portion indicated by a dashed-line framerepresents the time period of medical interference, curve (a) representsa measurement result of the first working electrode 2, curve (b)represents a measurement result of the second working electrode 3, and aplurality of dots (c) represent glucose concentration values measuredwith a conventional test strip using an analyzing instrument. FIG. 47 isa bar chart illustrating the difference of the measurement result ofFIG. 46 under the medical interference and without the medicalinterference.

As shown in FIGS. 44 and 45, when the implantable micro-biosensor is notsubjected to consumption of the interference, the values measured duringa time period under the medical interference is higher than the valuesmeasured using the conventional test strip. An average error valueduring the time period without the medical interference is −0.2 mg/dL.An average error value during the time period of the medicalinterference is 12.6 mg/dL. A total error value is 6.7 mg/dL. A meanabsolute relative difference during the time period of the medicalinterference is 10.6.

As shown in FIGS. 46 and 47, when the implantable micro-biosensor issubjected to consumption of the interference, the measurement resultsunder the medical interference is substantially the same as thoseobtained using the conventional test strip, and the average error valueduring the time period without the medical interference is 0.1 mg/dL.The average error value during the time period of the medicalinterference is −2.1 mg/dL. The total error value is −1.1 mg/dL. Themean absolute relative difference during the time period of the medicalinterference is 4.6.

The aforesaid results demonstrated that when the implantablemicro-biosensor of the disclosure is subjected to consumption of theinterference, the error value can be reduced significantly, such thatthe measurement accuracy can be enhanced.

In summary, in the implantable micro-biosensor according to thedisclosure, the first working electrode, the at least one second workingelectrode, and the at least one counter electrode are included, and arelative position of the first sensing section and the second sensingsection is assigned, such that the implantable micro-biosensor accordingto the disclosure not only can execute the measurement of the analyteand reduce the influence of the interfering substances, but also canregenerate the silver halide by applying a potential difference to thecounter electrode. Measurement of the analyte, reduction of theinfluence of the interfering substances, and regeneration of the silverhalide can be adjustably performed according to practical needs.Therefore, the implantable micro-biosensor according to the disclosurecan perform an accurate measurement of an analyte and has an extendedservice life, and can monitor a physiological parameter of an analytecontinuously.

In the description above, for the purposes of explanation, numerousspecific details have been set forth in order to provide a thoroughunderstanding of the embodiments. It will be apparent, however, to oneskilled in the art, that one or more other embodiments may be practicedwithout some of these specific details. It should also be appreciatedthat reference throughout this specification to “one embodiment,” “anembodiment,” an embodiment with an indication of an ordinal number andso forth means that a particular feature, structure, or characteristicmay be included in the practice of the disclosure. It should be furtherappreciated that in the description, various features are sometimesgrouped together in a single embodiment, figure, or description thereoffor the purpose of streamlining the disclosure and aiding in theunderstanding of various inventive aspects, and that one or morefeatures or specific details from one embodiment may be practicedtogether with one or more features or specific details from anotherembodiment, where appropriate, in the practice of the disclosure.

While the disclosure has been described in connection with what areconsidered the exemplary embodiments, it is understood that thisdisclosure is not limited to the disclosed embodiments but is intendedto cover various arrangements included within the spirit and scope ofthe broadest interpretation so as to encompass all such modificationsand equivalent arrangements.

What is claimed is:
 1. An implantable micro-biosensor for continuouslymonitoring a physiological parameter of an analyte in a body,comprising: a substrate having a first surface and a second surfaceopposite to said first surface; a first working electrode including afirst sensing section disposed on said first surface of said substrate,said first sensing section being driven by a first potential differenceso as to form a measuring region to measure a physiological signal inresponse to the physiological parameter of the analyte; at least onesecond working electrode disposed on said first surface of saidsubstrate and including a second sensing section proximate to said firstsensing section, said second sensing section being driven by a secondpotential difference to form an interference-eliminating region that isin touch with a surrounding of said first sensing section and at leastpartially overlaps with said measuring region, so as to consume aninterfering substance in the body approaching said first and sensingsections; and at least one counter electrode disposed on said first orsecond surface of said substrate and including a silver-silver halide,so as to cooperate with said first working electrode to measure thephysiological signal, to cooperate with said second working electrode toconsume the interfering substance, and to selectively cooperate withsaid first or second working electrode so as to be driven to regeneratesilver halide.
 2. The implantable micro-biosensor according to claim 1,further comprising a third working electrode disposed on said first orsecond surface of said substrate and proximate to said counterelectrode, said counter electrode selectively cooperating with saidthird working electrode so as to be driven to regenerate silver halide.3. The implantable micro-biosensor according to claim 2, wherein saidcounter electrode and said third working electrode are disposed on saidsecond surface of said substrate and are spaced apart from each other.4. The implantable micro-biosensor according to claim 1, wherein asurface material of said first sensing section includes a firstconductive material, and a surface material of said second sensingsection includes a second conductive material different from said firstconductive material.
 5. The implantable micro-biosensor according toclaim 4, further comprising a chemical reagent layer covering at least aportion of said first conductive material of said first sensing sectionand reacting with the analyte to generate a product.
 6. The implantablemicro-biosensor according to claim 5, wherein said first workingelectrode is driven by said first potential difference so as to permitsaid first conductive material to have a first sensitivity that isresponsive to the product, and said second working electrode is drivenby said second potential difference so as to permit said secondconductive material to have a second sensitivity that is responsive tothe product and that is smaller than said first sensitivity.
 7. Theimplantable micro-biosensor according to claim 4, wherein said firstconductive material is selected from the group consisting of a noblemetal, a noble metal derivative, and a combination thereof, and saidnoble metal is selected from the group consisting of gold, platinum,palladium, iridium, and combinations thereof.
 8. The implantablemicro-biosensor according to claim 4, wherein said first conductivematerial is platinum, and said first potential difference ranges from0.2 V to 0.8 V.
 9. The implantable micro-biosensor according to claim 4,wherein said second conductive material is carbon, and said secondpotential difference ranges from 0.2 V to 0.8 V.
 10. The implantablemicro-biosensor according to claim 1, wherein said second sensingsection is disposed along and spaced apart from at least one side ofsaid first sensing section by a distance of up to 0.2 mm.
 11. Theimplantable micro-biosensor according to claim 1, wherein said secondsensing section extends along and is spaced apart from at least aportion of a periphery of said first sensing section, and a ratio ofsaid portion of said periphery of said first sensing section to a totalperiphery of said first sensing section ranges from 30% to 100%.
 12. Theimplantable micro-biosensor according to claim 1, wherein the number ofsaid at least one second working electrode is two, said second sensingsections of said second working electrodes are disposed, respectively,along two opposite sides of said first sensing section of said firstworking electrode.
 13. The implantable micro-biosensor according toclaim 1, wherein said counter electrode comprise a mixture of saidsilver-silver halide and carbon.
 14. The implantable micro-biosensoraccording to claim 1, wherein said counter electrode at least includes afirst layer that contains said silver/silver halide, and a second layerthat contains a third conductive material for covering at least aportion of said first layer.
 15. The implantable micro-biosensoraccording to claim 1, which is operated perpendicularly to the skin ofthe body, wherein the implantable micro-biosensor has an implanting endportion with a length of up to 6 mm.
 16. A process for continuouslymonitoring a physiological parameter of an analyte in a body during amonitoring time period that includes at least one first time section formeasuring the analyte, at least one second time section for consuming aninterfering substance in the body, and at least one third time sectionfor regenerating silver halide, the process comprising the steps of: a)providing the implantable micro-biosensor according to claim 1; b)applying the first potential difference between the first workingelectrode and the counter electrode during the first time section topermit the first working electrode to have a potential higher than thatof the counter electrode so as to obtain the physiological signal; c)applying the second potential difference between the second workingelectrode and the counter electrode during the second time section topermit the second working electrode have a potential higher than that ofthe counter electrode so as to consume the interfering substance; and d)subjecting the counter electrode to be driven by a third potentialdifference so as to regenerate the silver halide.
 17. The processaccording to claim 16, wherein the first and second time sections atleast partially overlaps with each other.
 18. The process according toclaim 16, wherein the first and second time sections do not overlap witheach other.
 19. The process according to claim 16, wherein the secondand third time sections at least partially overlap with each other. 20.The process according to claim 16, wherein in step a), the implantablemicro-biosensor further includes a third working electrode disposed onthe first or second surface of the substrate and proximate to thecounter electrode, and in step d), the third potential difference isapplied between the counter electrode and the third working electrode topermit the counter electrode to have a potential higher than that of thethird working electrode so as to regenerate the silver halide.
 21. Theprocess according to claim 20, wherein the first, second, and third timesections fully overlap with one another.
 22. The process according toclaim 16, wherein the monitoring time period includes a plurality of thesecond time sections, adjacent two of which are separated from eachother by implementing an open circuit operation or by applying a zeropotential difference.
 23. The process according to claim 16, wherein instep d), an amount of the silver halide present in the counter electrodeis maintained in a safe range.
 24. The process according to claim 23,wherein the silver halide present in the counter electrode has aconsumption amount corresponding to the physiological signal, the thirdpotential difference is constant, and an execution time of step d) isdynamically modified according to the consumption amount of the silverhalide.
 25. The process according to claim 23, wherein the silver halidepresent in the counter electrode has a consumption amount correspondingto the physiological signal, an execution time of step d) is constant,and the third potential difference is dynamically modified according tothe consumption amount of the silver halide.